Conventionally, a liquid crystal display device has been widely used for the screen of a word processor and computer. In recent years, the liquid crystal display device has spread rapidly as a television screen. Many of these liquid crystal display devices adopt TN (Twisted Nematic) mode. However, the TN mode liquid crystal display device has the problems of tendencies to degrade a contrast and to reverse a gradation property when viewed from an oblique direction.
For this reason, in recent years, in light of the improvement in viewing angle property, a VA (Vertical Alignment) mode liquid crystal display device has been attracting attention. A liquid crystal cell of the VA mode liquid crystal display device is arranged in combination of a nematic liquid crystal having a negative dielectric anisotropy with a vertical alignment film.
Further, for example, Japanese Laid-Open Patent Publication No. 2000-39610 (Tokukai 2000-39610, published on Feb. 8, 2000, which is a counterpart publication to U.S. Pat. No. 6,339,460) and Japanese Patent No. 2947350 (granted on Jul. 2, 1999), as shown in FIGS. 20 and 21, respectively, disclose a liquid crystal display device 101 in which a biaxial film 116 is provided between a liquid crystal cell 111 and a polarizing plate 112; and a liquid crystal display device 101a in which a positive uniaxial film 114 and a negative uniaxial film 115 are provided between the liquid crystal cell 111 and the polarizing plate 112 and between the liquid crystal cell 111 and a polarizing plate 113, respectively, in order to compensate the optical anisotropy of the liquid crystal cell 111 when black image is displayed.
With the above arrangement, even though the liquid crystal cell 111 brings a phase difference depending on a polar angle to transmitting light when the liquid crystal cell 111 in which liquid crystal molecules are oriented vertically is viewed from an oblique direction, properly setting the respective retardations of the films 116 (114 and 115) can compensate the phase difference. Therefore, black displaying can be performed substantially as in the case when the liquid crystal cell 111 is viewed from a front direction, that is, as in the case where the liquid crystal molecules maintain the polarizing state of the transmitting light. As a result of this, it is possible to prevent light leakage, thus enhancing the contrast when viewed from an oblique direction.
However, under the situation where a liquid crystal display device with a wider viewing angle and higher display quality is expected, there is a demand for the improvement in contrast when viewed from an oblique direction nowadays. The liquid crystal display devices using the respective films 116 (114 and 115) with the retardations described in Japanese Patent No. 2947350 and Japanese Laid-Open Patent Publication No. 2000-39610, however, are not always satisfactory and still leave room for improvement.